Miniature snap action switches have found a ready application in a long list of products including counters, timers, door interlocks, thermostats, and equipments operating according to thermostatic control, valve controls, photocopy equipment, data processing equipment, calculators, recorders, record players, vending machines and the like. The usefulness of the switch results from a small size, from a variable operating force depending upon the mechanism of the switch, and from a relatively low cost.
In operating equipments in which the switches control the electrical circuit operation of the equipment, the mechanical and electrical characteristics required for the equipments vary significantly. For instance, door interlocks operating relatively few times a day in a fixed stable mounting, with an excessive operating force available, and with a stable contact position either in a closed-circuit or open-circuit position, provide conditions for a long life for the miniature snap action switch. However, in applications for the switches which are less stable, or are in portable or in moving equipments there can be bouncing at the contacts or breaking of contact unless a substantial force maintains the contact in circuit closing position. The contact force in turn affects the current carrying capacity at the contact and hence that characteristics of the switch, for the better and more secure the contact the greater the current carrying capacity. The available operating force will vary from application to application in equipments, but generally a light operating force is very desirable in many applications.
Normally, for such switch applications, that which provides the longest life so as to minimize replacement and maintenance for such switches in the equipment is the most acceptable. Acceptability is further enhanced with a low operating force for the switch and a maximum contact force to provide a large current carrying capacity, all at a reasonable cost. In the prior switches of this type these three characteristics are not maximized, and there is a need in the industry for a switch at a reasonable cost that does maximize all such requirements.